For scientists, researchers, and product developers, selecting the correct grade of Fluorescein (CAS 2321-07-5) is fundamental to the success of their projects. When you intend to buy Fluorescein, having a clear understanding of its key specifications ensures you are sourcing a product that meets your precise application needs. This checklist serves as a guide for procurement professionals and researchers alike.

1. Purity: The Cornerstone of Performance

The purity of Fluorescein directly impacts its fluorescent intensity and the absence of interfering signals. Look for specified purity levels, typically expressed as a percentage. For advanced research, microscopy, or diagnostic applications, aim for purity levels of 98% or higher. Reputable manufacturers, especially those in China, will provide this information prominently on their product datasheets and CoAs.

2. Appearance: Visual Confirmation

Fluorescein is generally described as a white to off-white or light yellow powder. While slight variations might exist between manufacturers, a significant deviation in color or texture could indicate impurities or degradation. Always check the product description for visual specifications.

3. Solubility: Formulating for Application

Understanding Fluorescein's solubility is critical for preparing solutions. Note its solubility in common solvents: generally insoluble in water but soluble in dilute alkaline solutions, ethanol, methanol, acetone, and DMSO. Confirm that the solvent system you plan to use is compatible with the Fluorescein you intend to buy.

4. CAS Number: Exact Identification

Always verify the CAS number: 2321-07-5. This unique identifier ensures you are procuring the specific compound you require, distinguishing it from related fluorescent dyes or derivatives.

5. Spectral Properties: Ensuring Fluorescent Performance

For fluorescence-dependent applications, noting the excitation and emission maxima is essential. Typically, Fluorescein has an excitation peak around 494 nm and an emission peak around 521 nm. Suppliers may provide this data, which is crucial for matching it with excitation light sources and emission filters.

6. Manufacturer/Supplier Reputation: Reliability Matters

When you search for a supplier, consider their reputation for quality, consistency, and customer service. For bulk purchases, establishing a relationship with a trusted manufacturer in China can provide both economic advantages and supply chain stability. Request sample batches if possible to validate performance before committing to larger orders.

By meticulously reviewing these specifications, you can confidently purchase Fluorescein (CAS 2321-07-5) that aligns with your project’s demands, ensuring optimal results and efficient use of resources.